Iron air battery

[Joeboy]

This might be old news?
https://formenergy.com/technology/battery-technology/

[Stinsy]

My understanding is that these batteries are astonishingly cheap per kWh and last forever, but the self-discharge rate is horrific.

You can get over the inefficiency if the power was otherwise "going to waste" (eg in cases of wind curtailment), but lithium batteries are much more efficient.

[martinW]

If you were using the stored energy during the day, and recharging at night would the 'horrific' self discharging rate be that much of an issue in reality?

I would think overall charge discharge efficency over 24 hours would be more relevant when cost be taken into account

[nowty]

From what I can find they only have a round trip efficiency of 50%, now I'm assuming thats only the battery efficiency which may not include AC to DC and DC to AC conversion which if true is pretty bad when compared with LA (90%) and lithium (95%+).

Also cycle life similar to LA Forklift cells, i.e. significantly less than lithium.

So as LA is extremely recyclable, I would say LA would be better and maybe more superior in self discharge but commercial battery companies have generally dumped LA in favour of lithium.

So maybe like flow batteries they might have a use in a very specific situation where there is a massive abundance of green overcapacity in a similar way to producing green hydrogen which has pretty poor conversion efficiency.